[T3] Invasion and Post Invasion Repairs

[Jim Adney]

On 9 Aug 2018 at 18:40, John LaFrancois wrote:

> Agreed if the bar is not hard along it's entire length then a mild slow
> cool down after welding is the way to go.  I would have thought that the
> torsion bars, to have much spring action, would be hard though. 

The amount of springyness is only a function of the metal's Young's 
Modulus, or Modulus of Elasticity. That's the same for all iron and steels. 
Hardening just extends the stress vs. strain curve. A non-hardened part will 
take a set (become permanently deformed) at some point, whereas a 
hardened part will continue to spring back. In other words, hardening will 
extend the elastic limit.

It looks like the VW engineers knew what they were doing, because these 
bars clearly never get pushed past their elastic limit. In fact, I don't think I've 
ever seen a broken sway bar, although lower bars and rear torsion bars 
have been known to fail.

I'd always assumed that all our torsion bars had been hardened. I'll have to 
check a lower bar. I think I've got a broken one downstairs. Now that I think 
about it, the fact that the lower bars have been prestressed, making lefts and 
rights different, makes me suspect that they are soft.

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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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